The continued development of circuit integration technology has allowed for an unprecedented degree of scaling and integration of digital circuitry. Large scale integrated circuits (IC) can allow for an overall reduction in the cost of the applications that make use of the integrated circuits.
However, a significant portion of an IC's overall cost can be due to production testing. This can be especially true when the IC is a complex mixed-signal IC used in RF wireless applications. The testing of these ICs may include standards compliance testing in addition to full functional (both digital and analog) testing. The standard testing procedure involves the functional and compliance testing of the IC after they have been packaged.
One disadvantage of the prior art is that the testing can require expensive and sophisticated test equipment. The potentially large expense can reduce the total number of test equipment available, therefore the testing can be a bottleneck in the production of the ICs.
A second disadvantage of the prior art is that the testing cannot be performed until after the ICs have been packaged. Then, if an IC is found to be defective, the IC (along with the package) may need to be discarded. This can be expensive, since the packaging can represent a large percentage of the cost of the IC. Alternatively, the IC may need to be removed from its package, but this can be difficult and time intensive.
A third disadvantage of the prior art is that the testing cannot usually be performed once the packaged IC leaves the factory. Therefore, testing in the field cannot be done to help diagnose performance issues that may arise during actual use, which may not be reproducible in the factory.